So how did Planck do it? The key lies in that strange quantity called Planck’s constant. Usually represented by the symbol ħ, this has the value (in scientific notation) of 1.05E-34 kgm2s-1. That looks horribly obscure, but it’s a fundamental property of the universe. It’s so fundamental, Planck argued, that it really ought to be given the value 1....
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So how did Planck do it? The key lies in that strange quantity called Planck’s constant. Usually represented by the symbol ħ, this has the value (in scientific notation) of 1.05E-34 kgm2s-1. That looks horribly obscure, but it’s a fundamental property of the universe. It’s so fundamental, Planck argued, that it really ought to be given the value 1. So he defined his units in such a way that ħ = 1.
From; http://mysteriousuniverse.org/2014/06/ma...